1. Field of the Invention
The invention relates to optical networking components. In particular, the invention relates to add/drop nodes.
2. Background of the Invention
Optical networks often include optical fibers for carrying a beam of light having a plurality of channels. Add drop nodes are often employed to add and/or drop channels from the beam of light.
A tunable add/drop node allows the channels added and/or dropped from the beam of light to be tuned. Many add/drop nodes have undesirably low tuning ranges. Further, add/drop nodes often have undesirably large power requirements. For the above reasons, there is a need for a tunable add/drop node having a wide turning range and/or reduced power requirements.
The invention relates to an add/drop node. The add/drop node includes a first filter configured to receive a light beam having a plurality of channels on an input waveguide. The first filter is also configured to direct channels having wavelengths falling within a plurality of first wavelength bands to a transition waveguide. The add/drop node also includes a second filter configured to receive the channels directed to the transition waveguide. The second filter is configured to direct channels having wavelengths falling within a plurality of second wavelength bands to a drop waveguide. The first filter and/or the second filter can be tunable.
In some instances, the first filter receives the light beam from an input waveguide. The first filter is also configured to receive a second light beam having one or more channels on an add waveguide and to direct channels that do not have wavelengths falling within the plurality of first wavelength bands from the add waveguide to the drop waveguide.
The invention also relates to a method of operating an add/drop node. The method includes selecting a target wavelength to be dropped by the add/drop node. The add/drop node has a first filter in optical communication with a second filter. The first filter is configured to direct channels having wavelengths falling within a plurality of first wavelength bands from an input waveguide to the second filter. The second filter is configured to direct channels having wavelengths falling within a plurality of second wavelength bands to a drop waveguide. The method also includes tuning the first filter such that a first wavelength band includes the target wavelength. In some instances, the method also includes tuning the second filter such that a second wavelength band includes the target wavelength.
Another embodiment of the method includes selecting a target wavelength to be dropped by the add/drop node. The add/drop node has a first filter in optical communication with a second filter. The first filter is configured to direct channels having wavelengths falling within a plurality of first wavelength bands from an input waveguide to the second filter. The second filter is configured to direct channels having wavelengths falling within a plurality of second wavelength bands to a drop waveguide. The method also includes tuning the second filter such that a second wavelength band includes the target wavelength.
Another embodiment of the method includes selecting a target wavelength to be added by the add/drop node. The node has a first filter in optical communication with a second filter. The first filter is configured to direct channels having wavelengths falling within a plurality of first wavelength bands from an add waveguide to a pass waveguide and to direct channels having wavelengths that do not fall within a plurality of first wavelength bands from the add waveguide to the second filter. The method also includes tuning the first filter such that a first wavelength band includes the target wavelength.